Conventionally, redistribution of an ethylenic double bond (metathesis reaction) using a carbene complex represented by the following formula 4
wherein M is selected from the group consisting of Os and Ru, X1 and X2 are each independently selected from anion ligands, L1 and L2 are each independently selected from neutral electron donors, R23 is selected from a hydrogen atom, a substituted or unsubstituted alkyl group and a substituted or unsubstituted aryl group is widely known (e.g., patent document 1). Furthermore, a method comprising using a carbene complex for a polymerization reaction, and directly using the complex as a catalyst for a hydrogenation reaction is also known (e.g., patent documents 2-5 and non-patent document 1).
A polymer obtained by hydrogenation of a polymer obtained by a metathesis reaction contains a large amount of a heavy metal derived from a catalyst used for the metathesis reaction or hydrogenation reaction. The presence of a large amount of a heavy metal in the hydrogenated polymer gives rise to the problems of coloring of resin and decreased heat resistance. Therefore, various methods for removing the residual catalyst have heretofore been studied. As such example, a method of removing a residual catalyst by the use of an adsorbent such as activated carbon, activated clay and the like is known (see patent document 6). This method, however, requires treatment of a polymer solution with the adsorbent, which increases the amount of the adsorbent to be used, and is economically disadvantageous. Moreover, the method is associated with the problems of easily deteriorated operability as evidenced by abnormal increase in the fluid pressure during the treatment step and the like, and easy contamination of polymer with adsorbent fine particles due to pulverization thereof. As a method of removing a residual catalyst, moreover, a method comprising repeating an operation to treat the resultant polymer with a poor solvent to allow precipitation is known (see non-patent document 1). Nevertheless, such method is hardly an industrial one since the operation is troublesome.    patent document 1: National Publication of International Patent Application No. H11-510807    patent document 2: JP-A-10-195182    patent document 3: JP-A-2002-348360    patent document 4: National Publication of International Patent Application No. 2002-509961    patent document 5: National Publication of International Patent Application No. 2002-525397    patent document 6: JP-A-2001-163958    non-patent document 1: Journal of Molecular Catalysis A; Chemical Vol. 190 (2002) pages 177-184